Electric cable connection devices like the one initially defined have, according to prior art, used an insulation part made of a thermosetting resin like epoxy, moulded directly on and forming a sleeve or bushing on the contact part and leaving a free end of the contact part for connection to a mating end of a cable. The thickness of the epoxy bushing has been adapted to the need of insulation capacity thereof in relation to an earthed element formed by a wall of an electric station protruded by the device. And since epoxy sets with small geometric tolerances, there has been no problem of achieving the required thickness for applications within the intermediate and high voltage field.
Subsequently to the interconnecting of the contact part and cable, an outer further insulating member, normally made of rubber and earthed, has been positioned like a sleeve or sock surrounding the mating ends of the contact part and cable, and also surrounding the end of the insulation part of the electric connection device. Over time the shape and outer dimension of the insulating part and the shape and dimension of the further insulating member have become worldwide standard.
Also the canisters of fuse-canisters of prior art has made use of an insulation part made of solid epoxy of a thickness sufficient to prevent short circuits from appearing between the voltage-carrying part and an earthed wall of an electric station protruded by the canister.
In order to achieve a less costly manufacture of the connection device, it has been conceived to use a thermoplastic resin instead of a thermosetting resin which is the more expensive one. EP 1 496 576 shows an electric cable connection device that uses an insulation part made of a thermoplastic resin, preferably polyamide.
However, the thermoplastic resin has the disadvantage of not being easily and readily moulded to the desired thickness in view of the required insulation properties of the electric connection device. Accordingly, the insulation part shown in EP 1 496 576 has a thickness of only 3-5 mm, which is insufficient from an insulation point of view, and thus has to be supplemented by further insulation. Moreover, since the insulation is moulded directly onto the outer periphery of the contact part, the shape and outer dimension of the insulation part is constricted to the shape and dimension of the outer periphery of the contact part. Accordingly, the standardized outer dimension of the insulation part that has been adopted with regard to the use of a thermosetting resin, preferably epoxy, will not be easily achieved by means of a thermoplastic resin. Of course, the dimension of the contact part could be adapted in order to enable the thermoplastic resin to obtain the desired outer dimension through an economic moulding process, but such a measure would rather make the total manufacturing cost higher than was previously the case when epoxy was used as the insulation material.